How to Make a One Piece Into a Tankini

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Learn how to make a one piece into a tankini. This refashion project is great for a one piece swimsuit that is too short or long in the torso.

I have a really long torso and find it really hard to get a one piece swimsuit that fits the way I want it too. I’m sure it’s the same for anyone with a short torso. It’s just really hard getting a swimsuit that is perfect.

I’m really picky about the swim bottoms I wear, but I’m more flexible about the swim top. This year I thrifted two one piece swimsuits with the intention of cutting them into two pieces. I wanted a cropped tankini style which meant I couldn’t save the bottom part, but I’ll show you how if that is what you want.

How to Make a One Piece Into a Tankini

What is refashioning?

Refashioning is to fashion clothing again or differently. I usually use this to describe when I’m sewing clothing to fit different or to look different, but the majority of the item stays the same.

refashioned swimsuit

Do you love to sew? Try one of these sewing projects:

refashioned swimsuit

How to Make a One Piece Into a Tankini


  • One piece swimsuit to cut
  • Sewing tools
  • Sewing machine
one piece swimsuit refashion


I don’t have a picture of this step because this completely depends on you and your body. Put the swimsuit on and decide what you want to cut it into.

It’s pretty tricky to get a long tankini from a one piece swimsuit because you might not have the length. You can get a cropped tankini or a bikini from a one piece swimsuit.

Mark where you want the bottoms to end and where you want the top to end. Remember that you’ll need hem allowance on both ends so that will change what you are able to do.

one piece swimsuit refashion


Take the swimsuit off and place it on a table and determine where the marks are.

Using a marking tool to continue the mark all the way across the swimsuit perpendicular to the grain. Then mark the hem allowance with one of these amounts:

  • 3/8 inch for a small elastic folded over edge
  • 1/2 inch for a small hem
  • 1 inch for a deep hem
  • 1 inch for 1 inch elastic for under the bust or for the waist

You will only be able to use both the top and the bottom if you can fit these hem allowances in between the two marks.

I cut both of my one piece swimsuits right above the leg openings because I wanted a cropped tankini with a 1 inch hem allowance.

cut through swimsuit
cut through swimsuit

Fixing the Sides

One piece swimsuits will go out for the hips, but if you are turning it into a tankini or bikini, you need to change the sides. I didn’t want the hem of the tankini to go out, so I straightened the sides on both of the swimsuits.

Sew each side seam from the waist straight down with a zigzag stitch or a serger.

straighten sides

This will straighten the hem so it doesn’t poke out, and it will keep it tight and in place around my waist.

straighten sides

Hemming or Adding Elastic

If you are adding elastic, sew the elastic onto the inside edge with a zigzag stitch. Then fold it under and secure with another zigzag stitch.

If you are hemming, fold up the bottom the amount you decided on and pin in place.

pin up bottom and sew

Sew the hem with a zigzag stitch to secure.

refashioned swimsuit

You finished!

refashioned swimsuit

If you make something using this sewing project, I’d love to see! Please share it on social media with the hashtag #heatherhandmade and tag me!

How to Make a One Piece Into a Tankini
heather sewing

I believe small sewing moments can create great joy. Find your own “right” way to sew. -Heather

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